Re: Spinlock performance on Athlon MP (2.4)

From: Alan Cox (alan_at_lxorguk.ukuu.org.uk)
Date: 07/31/03

  • Next message: Alan Cox: "Re: TSCs are a no-no on i386"
    To: "Scott L. Burson" <gyro@zeta-soft.com>
    Date:	30 Jul 2003 23:59:00 +0100
    
    

    On Mer, 2003-07-30 at 22:50, Scott L. Burson wrote:
    > First, and probably the reason you haven't heard more complaints about the
    > problem, its severity is evidently dependent on the size of main memory. At
    > 512MB it doesn't seem to be much of a problem (right, Mathieu?). At 2.5GB,
    > which is what I have, it can be quite serious. For instance, if I start two
    > `find' processes at the roots of different filesystems, the system can spend
    > (according to `top') 95% - 98% of its time in the kernel. It even gets
    > worse than that, but `top' stops updating -- in fact, the system can seem
    > completely frozen, but it does recover eventually. Stopping or killing one
    > of the `find' processes brings it back fairly quickly, though it can take a
    > while to accomplish that.

    Thats the well understood DMA bounce buffers problem. It should be
    better in current 2.4 or with something like the Red Hat enterpise
    kenrel or probably the -aa patches.

    Its nothing to do with AMD although it can in part depend on what I/O
    dvevices your system has how much data hits the bounce buffers

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/


  • Next message: Alan Cox: "Re: TSCs are a no-no on i386"

    Relevant Pages

    • Re: experiences beyond 4 GB RAM with 2.4.22
      ... Is there any thinkable way to ommit the bounce buffers and still ... > your I/O subsystem can't do the job your box will not perform ideally. ... > For some workloads its a huge win to have the extra RAM, ... send the line "unsubscribe linux-kernel" in ...
      (Linux-Kernel)
    • Re: cutting down on boot messages
      ... And you want more static buffers to store that in than now? ... You'd do better to have a boot time command line option to limit printk ... uncover some errors in the severity of certain messages. ... send the line "unsubscribe linux-kernel" in ...
      (Linux-Kernel)
    • Re: Make clean misses stuff in 2.6.0-test4.
      ... Which zaps the .config, ... I forgot that make install doesn't install modules (for that ... in some complaints about the modules for the smp kernel I'd accidentally ... send the line "unsubscribe linux-kernel" in ...
      (Linux-Kernel)
    • Re: [PATCH] [2.6] PPC64: log firmware errors during boot.
      ... > Netlink is the usual solution to this sort of problem. ... > would be reasonable to printk RTAS error events with a severity of ... determine the severity of an event without doing full parsing of the ... send the line "unsubscribe linux-kernel" in ...
      (Linux-Kernel)
    • Re: Sabotaged PaXtest (was: Re: Patch 4/6 randomize the stack pointer)
      ... > I am well aware of complaints by some people about this behaviour. ... > there is a separated kiddie and blackhat mode in the latest PaXtest version. ... I think we'll pass on the complexity. ... send the line "unsubscribe linux-kernel" in ...
      (Linux-Kernel)